How do you calculate concrete volume?
Volume comes from the shape and your dimensions (in metres). For a slab that is length × width × thickness; for a round column π/4 × diameter² × height. The number of elements multiplies the total and the allowance covers waste and compaction. For small amounts, work in bags of dry mix (± 0.012 m³ per 25 kg); above roughly 1 m³, ready-mix per m³ is cheaper.
Frequently asked questions
How much concrete is in 1 m³?
1 m³ is 1000 litres. A 25 kg bag of dry mix yields about 0.012 m³, so roughly 85 bags per m³.
What allowance should I use?
Add 5 to 10% for waste, compaction and uneven ground; nearer 10% on rough or excavated ground.
Which units do I enter?
All dimensions in metres (m). A 12 cm slab thickness is entered as 0.12.
Can I calculate several identical elements?
Yes. Enter one element’s dimensions and set "Number of elements" to the count of footings, columns or strips.